The present invention relates to a liquid crystal display apparatus capable of efficiently dissipating the heat which is generated in a housing.
These days, there have been prosperously used a luminescence type plasma display apparatus and a non-luminescence type liquid crystal display apparatus as a display unit, instead of a CRT (Cathode Ray Tube).
Of these display apparatuses, the liquid crystal display apparatus uses a liquid crystal panel serving as a transmission type light modulating element, and has an illumination device (hereinafter referred to “backlight device”) located behind the liquid crystal panel for irradiating light onto the latter. Further, the liquid crystal panel controls the transmission factor of the light irradiated from the backlight device so as to create an image.
As one of the advantageous features, the liquid crystal display apparatus has an external shape which can be thin, in comparison with a CRT. However, these years, there have been demanded liquid crystal display apparatuses having a thickness which is further thin. The thinner the liquid crystal display apparatus, the harder the formation of air passages for dissipating heat generated in a housing which gives the external shape of the liquid crystal display apparatus, the heat cannot be efficiently dissipated, resulting in occurrence of a problem of increasing the temperature of a thermally weak part thereof. Thus, for instance, JP-A-2006-208485 proposes a construction in which LEDs (Light Emitting Diodes) are used as a light source in the backlight device in a side light type liquid crystal display apparatus, and in which a light source mounting substrate is connected to a heat radiation member for dissipating the heat produced from the LEDs.
However, in the liquid crystal display apparatus disclosed in JP-A-2006-208485, the light source mounting substrate (which is a flexible substrate) arranged between the LEDs and the heat radiation member causes a problem of hindrance of heat radiation. Further, although the LEDs are arranged in proximity with a circuit board, no consideration has been made of the affection of the heat generated from the circuit board upon the heat radiation from the LEDs.
Since the LEDs, which constitute a heat source in a liquid crystal display apparatus incorporating a backlight device using the LEDS, locally generate heat, heat radiation should be made after the heat is once diffused, and accordingly, the thermal transmission path from the LEDs to a heat diffusion member has to have a lower thermal resistance. As factors which hinder the heat radiation from the LEDs, there are enamulated the blockage of the thermal transmission path from the LEDs to the heat diffusion member by electric wirings, and the interference of heat generation from a circuit board with the LED heat radiating portion.